The mother of murdered teenager Stephen Lawrence has accused coalition ministers of squandering advances in race relations arising from her campaign, the Macpherson inquiry into his death, and the London Olympics.

In a hard-hitting interview, Doreen Lawrence says the government risks returning the country to the intolerance and ignorance of the last century by turning its back on measures introduced to ensure equality.

A month ago, alarmed by moves to water down a key protection arising from Sir William Macpherson's inquiry into the death of her son, the campaigner wrote to the prime minister, the deputy prime minister, Nick Clegg, and the other major party leaders. She told the Guardian the letter had been ignored. An earlier communication seeking to establish relations with the coalition at the outset also went without reply.

In May the home secretary, Theresa May, announced a review of the public sector equality duty, the mechanism by which government policies are assessed to ascertain the impact they will have on minorities. The mechanism's critics equate the practice with bureaucracy and red tape. "With the new government in, the whole thing around race has changed completely," said Lawrence, who will unveil a series of events on Wednesday to mark the 20th anniversary next year of Stephen's murder.

"Race is definitely not on the government's agenda. They have done away with the stop-and-search recording. Even before they came in, they talked about changing things, particularly on stop and search; that they would do away with the forms and they have done that.

"I don't really understand it because we all want a society in which we can live safely and live freely and to have police officers doing what they need to do on the street. But when it comes to race, they feel as if they are doing us a favour rather than doing what is right."

The frustration has deep roots. "When the new policing minister [Nick Herbert, who has since left the government] came in, I wrote to him suggesting we could have a meeting to see what we have been doing over the years and to see how we could work together. He never replied to any of my letters; not once. [Former Labour home secretary] Jack Straw's office wrote to him as well. Various people tried to make a connection and he never responded and that just shows to me that as far as they are concerned, if we have made any inroads, it wasn't important to them."

The monitoring of equality is crucial, she said. "I think about what it was like before the inquiry and what we were going through – and what people on the street were going through – the inequality, within institutions and within their work. If we don't make a stand we will go back to those days and I don't think we should.

"I think sometimes people are so blasé because it doesn't affect them. It doesn't affect their lives or their family lives and so they don't think about others. They have no understanding about what their measures are doing to other people."

Stephen's mother has spoken in the first of a series of Guardian interviews with leading newsmakers in 2012, at the end of an extraordinary year. In January two decades of campaigning bore fruit when two men, Gary Dobson and David Norris, were jailed for life for Stephen's murder. She later had the accolade of being chosen to carry the Olympic flag at the opening ceremony.

Of London 2012, Lawrence said: "The community was so much for it; you saw enthusiasm and it was so infectious. It got people coming together … but I don't think we have kept that going. I think people have gone back into their old little worlds and the austerity doesn't help."

The schedule to be announced on Wednesday at an event at the Commons includes a criminal justice lecture in February, the 14th anniversary of the publication of Macpherson's report. A service will be held at St Martins-in-the-Fields to mark the anniversary of Stephen's death, and there will be a memorial lecture in September by Daniel Libeskind, who supervised the master plan for the buildings and memorials on New York's Ground Zero.

Lawrence continues to press for the location and arrest of others involved in Stephen's murder, and for the authorities to fully address claims police corruption hampered the hunt for the killers.

A coalition spokesperson said: "The government is committed to a fair society with equal treatment and equal opportunity. Dealing with racism is a key part of that commitment.

"We want to ensure public services meet our commitment to equal treatment, which is why we are reviewing whether the equality duty is operating as intended. This is about ensuring equality of treatment, not diluting protections."